Conventionally, cleaners of a type that is placed, for example, on an upper surface of a water tank of a toilet and gradually releases a cleaning component into a toilet bowl have been widely used. In recent years, however, tankless toilets have been increasingly used, and there is a need for toilet cleaners applicable to tankless toilets.
As such toilet cleaners, aqueous gel cleaner compositions that can be attached to inner hard surfaces of toilet bowls are proposed.
For example, PTL 1 discloses a gel cleaner composition that contains, as an essential component, a polyoxyethylene alkyl ether having a given structure.
PTL 2 discloses a gel cleaner composition that contains, as essential components, a polyoxyethylene alkyl ether having a given structure and ethanol and that has a specified viscosity.
PTL 3 describes a cleaner composition that contains, as essential components, a specific polyalkylene glycol, calcium chloride and/or magnesium chloride, and water.
However, conventional gel compositions as described in PTL 1 and 2 disadvantageously tend to lose their surface transparency upon drying and, moreover, become hardened or less soluble.
To address these problems such as opacification (whitening) upon drying, PTL 3 proposes improving the surface drying by adding calcium chloride and/or magnesium chloride. However, adding these salts disadvantageously makes it difficult to add an anionic surfactant or an amphoteric surfactant, which imposes restrictions on product design.
Ideally, a gel cleaner composition remains attached until it is completely released. However, conventional gel cleaner compositions disadvantageously have poor stability at high temperatures, and, for example, when the temperature in a toilet is considerably high in summer, such a gel cleaner composition tends to soften or liquefy to be less adhesive and likely to detach from a surface to which the composition have been attached.